Optical coherence tomography angiography at the acute phase of optic disc edema

Application of Optical Coherence Tomography Angiography in True and Pseudo-Optic Disc Swelling

Purpose

We evaluated the optic disc microvasculature in healthy subjects and patients with optic nerve head drusen (ONHD), active papilledema, and acute nonarteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).

Methods

This prospective, comparative case series included sixteen eyes with ONHD, thirty-one eyes with active papilledema, sixteen eyes with acute NAION, and thirty-two healthy eyes. The Optovue AngioVue OCT and OCTA Imaging System recorded peripapillary retinal nerve fiber layer (RNFL) thickness and vessel density maps from the radial peripapillary capillary (RPC) slab.

Results

Average RNFL thicknesses were greater in eyes with ONHD, papilledema, and NAION compared to control eyes (all Ps < 0.001), but this parameter did not differ among patient groups. The mean peripapillary vessel density did not differ between the ONHD and control groups (P=1.000), nor between the NAION and papilledema groups (P=0.216). However, this value in the ONHD and control groups was significantly higher than in the NAION and papilledema groups (all Ps < 0.05).

Conclusion

RPC density is influenced during the progression of conditions such as ONHD, papilledema, and NAION. Although a decrease in vessel density values has been observed in cases of true disc edema, further research is necessary to assess the potential of OCTA in differentiating between true and pseudo-optic disc edema.

Optical coherence tomography angiography analysis in patients with intracranial hypertension

INTRODUCTION

Evidence on peripapillary microvasculature in intracranial hypertension (IH) after the regression of papilledema is still scarce. The aim of this preliminary study was to determine the association between structural changes in the optic nerve and the retina and peripapillary microvasculature in patients with IIH.

METHODS

We conducted a retrospective study. The study included 39 eyes of 21 patients with IIH. Treatment for IIH and history of obesity were registered from each patient. Moreover, OCT analysis including retinal nerve fiber layer (RNFL) thickness and ganglion cell-inner plexiform layer (GCIPL) thickness, and OCTA analysis including perfusion density (PD) and flux index (FI) of the radial peripapillary capillary plexus were performed.

RESULTS

Correlation analysis revealed a high correlation between GCIPL thickness and peripapillary PD and FI (p < 0,05, r > 0,7), whereas the degree of correlation between RNFL thickness and peripapillary microvascular parameters was low (p < 0,05, r < 0,7). Patients with regressed papilledema had significantly lower GCIPL thickness and peripapillary PD than control subjects (p < 0,05).

CONCLUSION

Peripapillary microvascular measurements are highly correlated with GCIPL thickness in patients with IIH. Moreover, GCIPL thickness and peripapillary PD are significantly inferior in patients with regressed papilledema compared to control group. Thus, we suggested that peripapillary microvascular parameters may be an early indicator of optic nerve atrophy in patients with IIH.

Diagnostic dilemma of papilledema and pseudopapilledema

BACKGROUND

Papilledema is the optic disc swelling caused by increased intracranial pressure (ICP) that can damage the optic nerve and cause subsequent vision loss. Pseudopapilledema refers to optic disc elevation without peripapillary fluid that can arise from several optic disc disorders, with optic disc drusen (ODD) being the most frequent cause. Occasionally, pseudopapilledema patients are mistakenly diagnosed as papilledema, leading to the possibility of unneeded procedures. We aim to thoroughly examine the most current evidence on papilledema and pseudopapilledema causes and several methods for distinguishing between both conditions.

METHODS

An extensive literature search was conducted on electronic databases including PubMed and google scholar using keywords that were relevant to the assessed pathologies. Data were collected and then summarized in comprehensive form.

RESULTS

Various techniques are employed to distinguish between papilledema and pseudopapilledema. These techniques include Fundus fluorescein angiography, optical coherence tomography, ultrasonography, and magnetic resonance imaging. Lumbar puncture and other invasive procedures may be needed if results are suspicious.

CONCLUSION

Papilledema is a sight-threatening condition that may lead to visual affection. Many disc conditions may mimic papilledema. Accordingly, differentiation between papilledema and pseudopailledema is crucial and can be conducted through many modalities.

Optical coherence tomography angiography findings in optic disc drusen and idiopathic intracranial hypertension

PURPOSE

To evaluate the changes in peripapillary microvascularity in idiopathic intracranial hypertension (IIH) and optic disc drusen (ODD) patients, by comparing them with those in healthy individuals, via optical coherence tomography angiography (OCTA).

METHODS

Sixty-two eyes of 33 patients with ODD, 58 eyes of 30 patients with IIH, and 70 eyes of 70 healthy people were imaged for 6 × 6-mm optic disc scans on a spectral-domain OCTA. Vascular densities in superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) of ODD, IIH, and healthy eyes were compared with a one-way analysis of variance. Post-hoc analysis was performed with the Gabriel test.

RESULTS

There was a significant decrease in peripapillary vessel density in SCP, DCP, and CC in patients with IIH compared to the control group (p < 0.05). In ODD patients, especially peripapillary vessel density in DCP was significantly reduced compared to the control group (p < 0.05). Peripapillary vessel density in DCP was significantly lower in the IIH group than ODD group (p < 0.05).

CONCLUSIONS

Peripapillary vascular density may be affected during the course of the disease in both IIH and ODD. Compared to healthy individuals, the decrease in vascular density in these patients and the consequent decrease in perfusion in the peripapillary region may guide the pathogenesis of the complications in the course of these two diseases. Although vascular density in DCP and CC differs significantly between IIH and ODD, case-controlled studies are needed to evaluate the role of OCTA in the differential diagnosis of IHH and ODD.

Advantages and Pitfalls of the Use of Optical Coherence Tomography for Papilledema

PURPOSE OF REVIEW

Papilledema refers to optic disc swelling caused by raised intracranial pressure. This syndrome arises from numerous potential causes, which may pose varying degrees of threat to patients. Manifestations of papilledema range from mild to severe, and early diagnosis is important to prevent vision loss and other deleterious outcomes. The purpose of this review is to highlight the role of optical coherence tomography (OCT) in the diagnosis and management of syndromes of raised intracranial pressure associated with papilledema.

RECENT FINDINGS

Ophthalmoscopy is an unreliable skill for many clinicians. Optical coherence tomography is a non-invasive ocular imaging technique which may fill a current care gap, by facilitating detection of papilledema for those who cannot perform a detailed fundus examination. Optical coherence tomography may help confirm the presence of papilledema, by detecting subclinical peripapillary retinal nerve fiber layer (pRNFL) thickening that might otherwise be missed with ophthalmoscopy. Enhanced depth imaging (EDI) and swept source OCT techniques may identify optic disc drusen as cause of pseudo-papilledema. Macular ganglion cell inner plexiform layer (mGCIPL) values may provide early signs of neuroaxonal injury in patients with papilledema and inform management for patients with syndromes of raised intracranial pressure. There are well-established advantages and disadvantages of OCT that need to be fully understood to best utilize this method for the detection of papilledema. Overall, OCT may complement other existing tools by facilitating detection of papilledema and tracking response to therapies.  Moving forward, OCT findings may be included in deep learning models to diagnose papilledema.

Evaluation of Peripapillary and Macular Optical Coherence Tomography Angiography Characteristics in Different Stages of Papilledema

BACKGROUND

Prospective evaluation of optical coherence tomography (OCT) and OCT angiography (OCT-A) characteristics in different stages of papilledema in idiopathic intracranial hypertension (IIH).

METHODS

In this prospective, observational study patients of IIH with papilledema were recruited and divided into 3 groups-early/established (Group 1), chronic (Group 2), and atrophic papilledema (Group 3). Peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell inner plexiform layer (GC-IPL) were recorded on OCT. Peripapillary and macular perfusion was documented at superficial retinal, deep retinal, and choriocapillary level using OCT-A. The investigations were repeated at 3 months.

RESULTS

RNFL showed significant thinning in all groups on follow-up with the atrophic group showing maximum thinning ( P = 0.01-Group 3). GC-IPL was significantly reduced in all stages of papilledema at baseline compared with the controls. Thinnest GC-IPL was noted in the atrophic group (52.75 ± 7.44 μm; P = 0.00 in Group 3 vs controls) that showed further deterioration on follow-up. On Image J analysis, significant decrease was noted at various levels in the peripapillary and macular perfusion at baseline especially in the atrophic group which showed further deterioration noted on follow-up. The final visual acuity showed a statistically significant weak negative correlation with baseline RNFL (r = -0.306) and GC-IPL (r = -0.384) and moderately negative correlation with baseline superficial peripapillary retinal perfusion (r = -0.553). A significant negative correlation was seen between increasing grade of papilledema and superficial peripapillary retinal perfusion with both Image J and automated indices (r = -0.46; r = -0.61), respectively.

CONCLUSIONS

GC-IPL may help identify early damage in papilledema even in the presence of thicker RNFL. Significant vascular changes can be observed on OCT-A that may help predict the final visual outcome in papilledema due to IIH.

Recent advances in the use of optical coherence tomography in neuro-ophthalmology: A review

Optical coherence tomography (OCT) is an in vivo imaging modality that provides non-invasive, high resolution and fast cross-sectional images of the optic nerve head, retina and choroid. OCT angiography (OCTA) is an emerging tool. It is a non-invasive, dye-free imaging approach of visualising the microvasculature of the retina and choroid by employing motion contrast imaging for blood flow detection and is gradually receiving attention for its potential roles in various neuro-ophthalmic and retinal conditions. We will review the clinical utility of the OCT in the management of various common neuro-ophthalmic and neurological disorders. We also review some of the OCTA research findings in these conditions. Finally, we will discuss the limitations of OCT as well as introduce other emerging technologies.

Accuracy of peripapillary OCTA in patients with acute nonarteritic anterior ischemic optic neuropathy

OBJECTIVE

To evaluate the accuracy of peripapillary optical coherence tomography angiography (OCTA) segmentation in eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION) and healthy eyes.

METHOD

In this retrospective study, en face OCTA images of the optic disc of healthy eyes and eyes with unilateral acute NAION were obtained. The disc boundary and radial peripapillary capillary (RPC) segmentation were generated automatically by the instrument software and then corrected by 2 expert investigators. The frequency of segmentation errors and its impact on vessel density and nerve fibre layer (NFL) thickness measurements were evaluated.

RESULTS

Thirty-eight eyes of 38 subjects (18 in the healthy group and 20 in the acute NAION group) were studied. A misidentified disc border was noted in 5 healthy eyes (27.7%) and 19 eyes with NAION (95.0%; p < 0.001). Segmentation error at the RPC level was found in 6 healthy eyes (33.33%) and 19 eyes with NAION (95.0%; p < 0.001). The nerve fibre layer thickness and RPC density did not change statistically significantly after error corrections in both groups.

CONCLUSIONS

Misidentification of disc border and segmentation error of the RPC layer are common in OCTA images of the optic disc. Accuracy of OCTA imaging in disc boundary detection and RPC network segmentation is reduced in edematous optic discs following acute NAION.

Changes of Optic Disc and Macular Vessel Perfusion Density in Primary Angle Closure Glaucoma: A Quantitative Study Using Optical Coherence Tomography Angiograph

INTRODUCTION

This study aims to investigate the changes of retinal vascular system in primary angle closure glaucoma (PACG) and acute primary angle closure (APAC) by optical coherence tomography (OCT) angiograph (OCTA) and to evaluate the diagnostic ability of changes of vessel density (VD) in different sectors and layers of optic disc and macular area in APAC and PACG.

METHODS

In this cross-sectional, observational study, 21 APAC patients (22 eyes) and 21 PACG patients (27 eyes) along with 17 healthy people were enrolled from August 2018 to March 2019. Optic disc region and macular region were imaged using swept-source OCTA system. VD of the macular region was quantified by Image J (1.52a, USA) and Matlab 2018a. The circumpapillary retinal nerve fiber layer (cpRNFL) thickness and ganglion cell complex thickness were obtained by spectral-domain OCT.

RESULTS

Compared with the healthy group, the cpRNFL thickness in superior sector was thicker in the APAC group, and this area had the most diffuse microvascular dropout as well. The difference in the macular superficial capillary plexus (SCP) VD between APAC and the control group was not statistically significant. The area under the ROC curves (AUC) of the total optic disc VD in the radial peripapillary capillary (RPC) layer was higher than the AUC of the papillary VD in the optic nerve head (ONH) layer. Compared to the control group, the total optic disc VD, peripapillary VD, and each quadrant of peripapillary VD were decreased in PACG (p < 0.01). In PACG macular region, SCP VD, and deep capillary plexus (DCP) VD, parafovea VD (except temporal sectors) decreased (p < 0.01). The PACG eyes had a greater decrease percentage of VD in total ONH than total macula. The diagnostic value of the VD in the ONH layer and the RPC layer was similar. The diagnostic value of the SCP VD in the macula was greater than the DCP VD in the macula. The AUC was no significant difference between cpRNFL thickness and the total optic disc VD AUC.

CONCLUSION

Elevated intraocular pressure preferentially affects vascular perfusion in the optic disc region more than the macular region in APAC and PACG. In the APAC eyes, there was a perfusion defect in the optic disc region and an increase in RNFL thickness. In this study, the OCTA vascular parameters have similar performance to the OCT structural parameters for glaucoma diagnosis in PACG.

Evaluation of Retinal Vascular and Structural Alterations in Pediatric Idiopathic Intracranial Hypertension Patients without Papilledema

PURPOSE

The aim of this study was to evaluate retinal structural and microvascular alterations using optical coherence tomography-angiography (OCTA) in pediatric idiopathic intracranial hypertension (IIH) patients with regressed papilledema.

METHODS

This study included 40 eyes of 21 IIH patients and 69 eyes of 36 healthy controls. Radial peripapillary capillary (RPC) vessel density and peripapillary retinal nerve fiber layer (RNFL) thickness were evaluated by XR Avanti AngioVue OCTA (Optovue, Fremont, CA, USA). The data were obtained from measurement zones that are automatically divided into two equal hemispheres (superior and inferior) and eight quadrants (superior-temporal, superior-nasal, inferior-temporal, inferior-nasal, nasal-superior, nasal-inferior, temporal-superior, temporal-inferior). Initial cerebrospinal fluid (CSF) pressure, grade of papilledema, and duration of follow-up were recorded.

RESULTS

There were significant differences in RPC vessel densities and RNFL thicknesses between the study groups (p ˃ 0.05). Significantly higher RPC vessel density measurements were observed in the patient group for the whole image, peripapillary, inferior-hemi, and whole nasal quadrants (p < 0.05). Except for the temporal-superior, temporal-inferior, inferior-temporal, and superior-temporal quadrants, the RNFL in all regions was significantly thicker in the IIH group than in the control group (p ˂ 0.001).

CONCLUSIONS

RNFL thickness and RPC vessel density were significantly different between the IIH patient and control groups, suggesting that retinal microvascular and subclinical structural changes that were potentially secondary to CSF pressure can persist after the resolution of papilledema. However, our results should be confirmed by further longitudinal studies investigating the progress of these alterations to determine their effects on peripapillary tissues.

Diagnosis of Optic Disc Oedema: Fundus Features, Ocular Imaging Findings, and Artificial Intelligence

Optic disc swelling is a manifestation of a broad range of processes affecting the optic nerve head and/or the anterior segment of the optic nerve. Accurately diagnosing optic disc oedema, grading its severity, and recognising its cause, is crucial in order to treat patients in a timely manner and limit vision loss. Some ocular fundus features, in light of a patient's history and visual symptoms, may suggest a specific mechanism or aetiology of the visible disc oedema, but current criteria can at most enable an educated guess as to the most likely cause. In many cases only the clinical evolution and ancillary testing can inform the exact diagnosis. The development of ocular fundus imaging, including colour fundus photography, fluorescein angiography, optical coherence tomography, and multimodal imaging, has provided assistance in quantifying swelling, distinguishing true optic disc oedema from pseudo-optic disc oedema, and differentiating among the numerous causes of acute optic disc oedema. However, the diagnosis of disc oedema is often delayed or not made in busy emergency departments and outpatient neurology clinics. Indeed, most non-eye care providers are not able to accurately perform ocular fundus examination, increasing the risk of diagnostic errors in acute neurological settings. The implementation of non-mydriatic fundus photography and artificial intelligence technology in the diagnostic process addresses these important gaps in clinical practice.

The Role of Optical Coherence Tomography Angiography in Optic Nerve Head Edema: A Narrative Review

Optic nerve head (ONH) edema is a clinical manifestation of many ocular and systemic disorders. Ocular and central nervous system imaging has been used to differentiate the underlying cause of ONH edema and monitor the disease course. ONH vessel abnormalities are among the earliest signs of impaired axonal transportation. Optical coherence tomography angiography (OCTA) is a noninvasive method for imaging ONH and peripapillary vessels and has been used extensively for studying vascular changes in ONH disorders, including ONH edema. In this narrative review, we describe OCTA findings of the most common causes of ONH edema and its differential diagnoses including ONH drusen.

Vascular supply of the optic nerve head: implications for optic disc ischaemia

The vascular supply of the optic nerve head is complex and remains incompletely delineated. Over the past 50 years, various investigators have attempted to clarify the relative contributions of the choroid, the short posterior ciliary arteries and the central retinal artery to the vascular beds of the inner retinal, prelaminar, laminar and retrolaminar segments of the nerve head. Conflicting theories have evolved, in no small part due to differing techniques of study, involving both flow parameters and anatomical constructs. These have included studies, both in normal subjects and in those with optic nerve ischaemia, of histopathology, electron microscopic corrosion casting, orbital colour Doppler flow studies, fluorescein angiography, indocyanine green angiography, laser Doppler flow studies, laser speckle flowgraphy, microperfusion and labelling studies and optical coherence tomography angiography. The nature of the optic disc, peripapillary retina and choroid microvasculature has implications for the pathophysiology of ischaemic optic neuropathy.

Quantitative Analysis of Radial Peripapillary Capillary Network in Patients With Papilledema Compared with Healthy Subjects Using Optical Coherence Tomography Angiography

BACKGROUND

To quantitatively compare the peripapillary microvascular network between patients with papilledema and healthy subjects using swept source optical coherence tomography angiography.

METHODS

In this retrospective observational study, patients with papilledema secondary to idiopathic intracranial hypertension and healthy controls were imaged with swept source optical coherence tomography angiography (PLEX Elite 9000; Carl Zeiss Meditec, Dublin, CA) using a 6 × 6 mm scan pattern centered on the optic disc. The capillary perfusion density (CPD) and capillary flux index (CFI) of the radial peripapillary capillaries in the retinal nerve fiber layer (RNFL) were calculated using Zeiss algorithm.

RESULTS

Thirty-nine eyes of 20 patients with papilledema and 66 eyes of 33 healthy subjects were imaged. The mean (P < 0.01), superior (P < 0.01), inferior (P < 0.01), and temporal (P = 0.02) CPD significantly differed between both groups. No significant difference was found between both groups for the CFI. The mean (P < 0.01), superior (P < 0.01), inferior (P = 0.01), temporal (P < 0.01), and nasal (P < 0.01) quadrants of the RNFL were positively associated with the CFI. The mean (P < 0.01), superior (P = 0.01), inferior (P = 0.01), temporal (P < 0.01), and nasal (P = 0.01) quadrants of the RNFL were negatively associated with the CPD.

CONCLUSION

Our study showed a decreased peripapillary capillary density without changes in flux intensity in eyes with papilledema. There were a positive association between the CFI and the RNFL and a negative association between the CPD and the RNFL. It confirmed the discriminatory ability of OCTA in differentiating a papilledema secondary to IIH from a normal optic disc, while providing complementary information for understanding papilledema pathophysiology.

Clinical profile and retinal nerve fibre layer thickness of optic disc oedema patients at a tertiary care institute in North India

Background:

Optic disc oedema (ODE) is an important manifestation in various ocular as well as systemic disorders. Measurement of retinal nerve fibre layer (RNFL) thickness in ODE patients may help in monitoring the progress of the disease and treatment response.

Objective:

To assess the clinical characteristics, aetiology and retinal nerve fibre layer (RNFL) imaging features of optic disc oedema (ODE) patients.

Design:

A retrospective observational study.

Methods:

This hospital-based study included performed for patients presenting with unilateral or bilateral ODE at the ophthalmology outpatient department of a tertiary institute between January 2019 and December 2019. Clinical features of all ODE patients were noted. RNFL thickness was measured by spectral-domain optical coherence tomography (Cirrus 500, Carl Zeiss Meditec, Dublin, CA, USA).

Results:

Sixty-four patients with ODE were seen with female preponderance (56.2%). The mean age of presentation was 36.8 ± 13.8 years. Bilateral ODE was seen in 57.8% patients. The most common cause of bilateral ODE was idiopathic intracranial hypertension (IIH) and vascular papillopathy. Retinal vein occlusion (RVO)-associated ODE was the most common unilateral presentation. Presenting visual acuity was best with IIH and worst with anterior ischaemic optic neuropathy (AION). The mean duration of symptoms was maximum with intracranial space-occupying lesion associated papilloedema and minimum with AION. The mean RNFL thickness was highest in uveitis-associated ODE, followed by compressive ON, and IIH. A positive correlation was noted between clinical ODE severity and RNFL thickness. All aetiological categories (except uveitic and compressive) had maximum RNFL thickening in the inferior quadrant and minimum in the temporal quadrant.

Conclusion:

The current study provides a clinical profile and RNFL measurements of ODE patients at this locality. The clinical severity of ODE correlated positively with RNFL thickness and most of the categories of ODE followed the normative pattern of RNFL thickness (inferior > superior > nasal > temporal) despite thickening.

The Value of Optical Coherence Tomography Angiography (OCT-A) in Neurological Diseases

Optical coherence tomography angiography (OCT-A) was commercially introduced in 2014. OCT-A allows a fast, non-invasive, three-dimensional analysis of the retinal vasculature from the vitreoretinal interface to the choriocapillaris. The results can be evaluated separately in automated or custom-defined retinal layers. Since its introduction, OCT-A has also been used in patients with neurological diseases in order to find and characterize retinal biomarkers. Many neurological diseases have retinal manifestations, often preceding the key symptoms of the neurological disease. Anatomically and developmentally, the retina is a part of the brain. In contrast to the brain, the retina is easily accessible for imaging methods; moreover, retinal imaging is more cost-effective than brain imaging. In this review, the current knowledge about OCT-A findings and possible OCT-A biomarkers in neurological diseases is summarized and discussed regarding the value of OCT-A as a diagnostic tool in neurological diseases.

Varicella-zoster virus infection presenting with unilateral keratouveitis and papillitis in an immunocompetent adult

We report a case of unilateral varicella-zoster virus (VZV) related keratouveitis and papillitis. A 54-year-old male presented with headache, left forehead rash, and decreased vision in the left eye. Examination of the left eye showed visual acuity (VA) of 0.15, relative afferent pupillary defect, anterior stromal corneal edema, nongranulomatous keratic precipitates, a swollen and hyperemic optic disc. The patient could read 6/12 of the Ishihara plates in the left eye. Optical coherence tomography (OCT) showed optic disc edema and OCT angiography (OCTA) revealed increased peripapillary vascularity. Computerized visual field testing demonstrated an enlarged blind spot and lower altitudinal defect. Serum anti-varicella-zoster IgM antibody level was elevated. The patient was put on oral acyclovir and prednisone treatment. At 1-month follow-up visit, VA increased to 0.9 and color vision was 11/12 Ishihara plates. OCT showed resolution of optic disc edema and OCTA demonstrated normalization of the increased peripapillary vascularity. Computerized visual field test demonstrated improvement in the lower altitudinal visual field defect and normalization of the enlarged blind spot. Optic nerve involvement in VZV infection occurs rarely, especially in immunocompetent patients as in our case.

Comparison of Peripapillary Vessel Density of Acute Nonarteritic Anterior Ischemic Optic Neuropathy and Other Optic Neuropathies With Disc Swelling Using Optical Coherence Tomography Angiography: A Pilot Study

BACKGROUND

The purpose of this study is to quantitatively compare the peripapillary vessel density (PPVD), measured with optical coherence tomography angiography (OCT-A), between acute nonarteritic anterior ischemic optic neuropathy (NAION) and other causes of disc swelling ("others").

METHODS

In this prospective comparative case series, patients with unilateral disc swelling due to acute NAION (n = 7) and "others" (n = 7) underwent OCT-A scanning of the optic nerve head with a swept-source OCT (Triton DRI-OCT), in addition to functional assessment. OCT-A images were analyzed using an automated customized MATLAB program. Comparison was made between total and 6 sectoral PPVD (radial peripapillary capillary [RPC] and choroid layers) of affected and fellow eyes; and between the 2 groups' affected eyes. Five NAION patients had repeated assessments at 1, 3, and 6 months.

RESULTS

Acute NAION eyes had a significantly lower total and superonasal PPVD (both layers) compared to fellow eyes. No such difference was observed in "others" group for the RPC layer. NAION eyes also had significantly lower total RPC PPVD than affected eyes in the "others" group. Over 6 months, NAION eyes had persistently lower RPC PPVD compared to fellow eyes but the reduced choroidal PPVD resolved by 1 month.

CONCLUSION

The study demonstrated reduced superonasal and total RPC PPVD in acute NAION, which persisted over 6 months. Because there is currently no single diagnostic test for NAION, use of OCT-A images to analyze RPC PPVD may potentially help distinguish acute NAION from other causes of disc swelling by quantitatively demonstrating capillary dropout in the RPC layer.

The association of cerebrospinal fluid pressure with optic nerve head and macular vessel density

The present study aims to investigate the effect of temporary cerebrospinal fluid pressure (CSFP) reduction on optic nerve head (ONH) and macular vessel density (VD) using optical coherence tomography angiography. Forty-four eyes of 44 adults with diagnostic lumbar puncture and CSFP reduction were recruited. Thirty-two eyes of 32 healthy volunteers were controls. ONH and macular VD images were evaluated differences between baseline and after CSFP reduction. The results showed that the mean CSFP decreased from (11.6±2.1) mmHg to (8.2±3.4) mmHg (P<0.001). VD in the macular regions decreased significantly after CSFP reduction in the study group (all P<0.05). The control group showed no significant changes in macular VD (all P>0.05). In the study group, decreased VD in the macular parainferior region was associated with CSFP reduction (R²=0.192, P=0.003), the reduction of macular VD in parafoveal (R²=0.098, P=0.018), parainferior (R²=0.104, P=0.021), parasuperior (R²=0.059, P=0.058), paranasal (R²=0.057, P=0.042), paratemporal (R²=0.079, P=0.026) was associated with mean ocular perfusion pressure decrease following CSFP reduction. ONH vessel density did not differ after CSFP reduction (all P>0.05). In conclusion, macular vessel density decreased in association with CSFP reduction. Retinal vessel density in the macular region is more sensitive than that in peripapillary region after CSFP reduction.

Evaulating peripapillary vessel density ın regressed papilledema ın ıdiopathic ıntracranial hypertension patients

PURPOSE

To evaluate the retinal nerve fiber layer (RNFL) thickness, the ganglion cell complex (GCC) and vessel density of the radial peripapillary capillary (RPC) plexus of eyes with regressed papilledema in idiopathic intracranial hypertension (IIH) patients using optical coherence tomography angiography (OCT-A) and comparing the results with healthy controls.

MATERIALS AND METHODS

Fifty-one eyes of 31 patients diagnosed with IIH and 52 eyes of 52 healthy subjects were enrolled in this study. All patients underwent a complete ophthalmological examination and a 4.5 × 4.5 mm peripapillary OCT-A scanning. The quantitative results of the peripapillary RNFL and GCC thicknesses and vessel density of the RPC were analyzed.

RESULTS

The vessel density in the inferior, superior nasal, and inferior nasal sectors of the patients with IIH significantly exceeded the vessel density of the healthy controls (P = 0.008, P = 0.008, and P = 0.000, respectively). The RNFL and GCC thickness measurements were comparable in both groups.

CONCLUSIONS

Patients with IIH show vascular abnormalities in the inferior nasal region, which can be detected with OCT-A. As a noninvasive imaging modality, OCT-A could provide a new perspective for understanding the pathophysiology of IIH and could also be useful in the follow-up of these patients.

A practical guide to optical coherence tomography angiography interpretation

Background

Optical coherence tomography angiography (OCTA) can image the retinal vasculature in vivo, without the need for contrast dye. This technology has been commercially available since 2014, however, much of its use has been limited to the research setting. Over time, more clinical practices have adopted OCTA imaging. While countless publications detail OCTA’s use for the study of retinal microvasculature, few studies outline OCTA’s clinical utility.

Body

This review provides an overview of OCTA imaging and details tips for successful interpretation. The review begins with a summary of OCTA technology and artifacts that arise from image acquisition. New methods and best practices to prevent image artifacts are discussed. OCTA has the unique ability among retinovascular imaging modalities to individually visualize each retinal plexus. Slabs offered in standard OCTA devices are reviewed, and clinical uses for each slab are outlined. Lastly, the use of OCTA for the clinical interpretation of retinal pathology, such as diabetic retinopathy and age-related macular degeneration, is discussed.

Conclusion

OCTA is evolving from a scientific tool to a clinical imaging device. This review provides a toolkit for successful image interpretation in a clinical setting.

Optical coherence tomography angiography in neuro-ophthalmology: Current clinical role and future perspectives

Optical coherence tomography angiography (OCTA) is a noninvasive, depth-resolved imaging tool for the appraisement of retinal vascular changes. Since its introduction, the understanding of diabetic retinopathy, age-related macular degeneration, central serous retinopathy, and other diseases has been enriched on many fronts. Its dyeless imaging property maps retinal as well as deeper choroidal vasculature in quick succession with good reproducibility. Hence, it can play an important role in the diagnosis and management of optic nerve-related diseases as well. A detailed literature review for its role in nonarteritic anterior ischemic optic neuropathy, papilledema, optic disc drusen, papillitis, hereditary optic neuropathies, central nervous system diseases, and others highlights its role. The whole spectrum of neuro-ophthalmological diseases shows consistent peripapillary and macular capillary changes with structural and functional correlation. The superficial and deeper retinal and choroidal vasculatures are affected depending on the nature of the disease process. Hence, OCTA positions itself as a useful, noninvasive tool in the armamentarium of a neuro-ophthalmologist in future; however, there are several limitations of the OCTA with respect to its technical abilities in challenging neuro-ophthalmic cases. Therefore, future research should be directed to enhance the technical capabilities of OCTA and to determine the more precise role of it in the prognosis of neuro-ophthalmic diseases.

Peripapillary Vessel Density Measured by Optical Coherence Tomography Angiography in Idiopathic Intracranial Hypertension

BACKGROUND

Although alterations in the peripapillary retinal nerve fiber layer (RNFL) in patients with idiopathic intracranial hypertension (IIH) have been characterized using optical coherence tomography (OCT), there are little data regarding the peripapillary vasculature in this patient population. Our aim was to evaluate findings of OCT angiography (OCT-A) in the peripapillary region in addition to the RNFL measurements on OCT in patients with IIH.

METHODS

Thirty-eight eyes of 19 patients with IIH and 42 eyes of 21 healthy controls were enrolled in our study. Papilledema was graded according to the Frisen scale. Peripapillary RNFL and vessel density were evaluated with OCT and OCT-A, respectively.

RESULTS

RNFL thickness was found to be increased with OCT, but this was statistically significant only in the inferior location in IIH patients when compared with the control group. There was a significant decrease in mean peripapillary vessel density measured with OCT-A in IIH patients with papilledema when compared with the control group (P < 0.05).

CONCLUSIONS

In patients with IIH, there was a decrease in peripapillary vessel density measured by OCT-A, and this decrease may be a consequence of the swelling of axons in the peripapillary retina due to papilledema. However, autoregulatory vascular mechanisms may also play a role in decreased peripapillary vessel density.

An Update on Imaging in Idiopathic Intracranial Hypertension

Neuroimaging plays an essential role in the diagnostic workup of idiopathic intracranial hypertension with the aims to exclude secondary causes of elevated intracranial pressure and to identify imaging signs that are commonly observed in this disorder. As a valuable expansion of brain imaging, the imaging of the retina using optical coherence tomography has been of increasing value. In particular, this is the case with the latest devices that allow a more accurate distinction between a reduction in retinal nerve fiber layer thickness due to an improvement of papilledema or due to a worsening caused by optic nerve atrophy. Although optical coherence tomography does not yet replace the other elements of the diagnostic workup, it is likely to play an increasing role in diagnosis and follow-up of idiopathic intracranial hypertension. The review focuses on the main findings in neuroimaging, including structural and vascular alterations as well as on the relevance of optical coherence tomography.

An update on idiopathic intracranial hypertension in adults: a look at pathophysiology, diagnostic approach and management

Idiopathic intracranial hypertension is a neurological syndrome determined by a rise in intracranial pressure without a detectable cause. Course and prognosis may be changeable, requiring a multidisciplinary approach for its diagnosis and management. Although its precise pathogenesis is still unknown, many studies have been carried out to define the possible causal and associated factors, such as retinoids, steroid hormones, body mass index and recent weight gains, cytokines and adipokines levels. The clinical presentation can be variable including chronic headache, disturbance of vision, diplopia and tinnitus. Even if papilloedema is considered the most specific sign, it could not be observed in more than 5% of patients during the evaluation of the fundus oculi. Neuroradiological signs acquire greater importance in patients who do not present papilloedema and may suggest the diagnosis of idiopathic intracranial hypertension. Other assessments can be useful in the diagnostic process, such as optical coherence tomography, visual evoked potentials, ocular ultrasonography and fundus fluorescein angiography and autofluorescence. Nonetheless, cerebrospinal fluid pressure measurement is required to establish a definite diagnosis. Management may be different, since surgical procedures or lumbar punctures are often required when symptoms develop rapidly leading to a loss of visual function. Apart from these cases, patients can be treated with a pharmacological approach and low-calorie diet, but they also need to be monitored over time since relapses years later are not uncommon.

Optical coherence tomography use in idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is a condition in which elevated pressure in the cerebrospinal fluid can lead to optic nerve head (ONH) dysfunction and subsequent visual impairment. Physicians are currently limited in their ability to monitor and manage this condition, as clinical symptoms and exam findings are often delayed in response to changes in intracranial pressure. In order to find other biomarkers of disease, researchers are using imaging modalities such as optical coherence tomography (OCT) to observe microscopic changes in the eye in this condition. OCT can create 2-dimensional and 3-dimensional high definition images of the retina of the ONH and has been used to study various conditions such as glaucoma and multiple sclerosis. Numerous studies have used OCT in IIH as well, and they have shown that certain retinal layers and the ONH change in thickness and shape in both the short and long term with intracranial pressure changes. OCT is a promising modality for clinical and scientific evaluation of IIH as it is a noninvasive and practical tool to obtain in depth images. This review will discuss how OCT can be used to assess a patient with IIH, both before and after treatment, along with its limitations and future applications.

Assessment of peripapillary vessel density in acute non-arteritic anterior ischemic optic neuropathy

PURPOSE

To assess the peripapillary perfusion in eyes with acute non-arteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).

METHODS

Twenty-five patients with unilateral acute NAION were included in this observational cross-sectional study. They were divided into two groups: group I (25 eyes) included eyes with acute NAION, and group II (25 eyes) included fellow normal eyes. Diagnosis of NAION was based on clinical examination and fluorescein angiography. OCTA (AngioVue, Optovue) was used to evaluate the optic nerve head perfusion and measure the peripapillary vessel density in all eyes included in the study.

RESULTS

Fourteen male and 11 female patients with a mean age of 60.2 ± 3.5 years were included in this study. The mean duration of presentation was 4.3 ± 0.6 days. Mean BCVA was 0.13 ± 0.06 and 0.69 ± 0.18 in eyes with NAION and normal eyes, respectively (p < 0.001). The peripapillary vessel was significantly decreased in all eyes with NAION compared with normal ones (p < 0.001). Two morphological changes were noted in eyes with NAION: vascular dropout related to area of disc edema in 25 eyes (100% of eyes) and vascular dilatation with tortuosity in 17 eyes (68%).

CONCLUSION

Eyes with NAION have decreased peripapillary vessel density with peripapillary vascular dilatation and tortuosity as assessed by OCTA.

Novel advances in monitoring and therapeutic approaches in idiopathic intracranial hypertension

PURPOSE OF REVIEW

The current article appraises the recent developments in idiopathic intracranial hypertension (IIH), with particular attention to novel therapeutic avenues and advanced clinical assessment and monitoring with optical coherence tomography and telemetric intracranial pressure devices.

RECENT FINDINGS

The incidence of IIH is increasing. The first consensus guidelines for IIH have been published detailing investigation and management algorithms for adult IIH. Improved understanding, clinical assessment and monitoring are emerging with the use of optical coherence tomography. Intracranial pressure telemetry is providing unique insights into the physiology of raised intracranial pressure in IIH. There are now an increasing number of ongoing clinical trials evaluating weight loss methods and novel targeted therapies, such as 11ß-HSD1 inhibition and Glucagon-like peptide 1 (GLP-1) receptor agonists.

SUMMARY

Several studies are evaluating new therapies for IIH. Monitoring techniques are advancing, aiding diagnosis and allowing the clinician to accurately evaluate changes in papilloedema and intracranial pressure.